Staten Island, NY has many red light cameras. The yellow light length varies with the flow of traffic. If traffic is average, the yellow light lasts a few seconds. If traffic is heavy, there isn't any red light, it goes from green to red immediately. This happened to me, with no yellow light. Shortly afterwards, the local newspaper reported this yellow light interval as being variable. Of course if you already received a ticket, it did not help, the fine was paid. Nothing was retroactive.